Beginning in the late ‘60s, this period of socio-political instability was marked by riots, strikes, protests, assassinations and terrorism. Extreme groups from the neo-fascist right, such as the National Vanguard, and the Marxist left, like The Red Brigade, violently wrestled for control, almost bringing Italy to its knees in the process.

As is often the case, these years of misery and division helped inspire a prolific period in cinema. An Italo-crime sub-genre – referred to as Poliziotteschi – produced memorable films such as Fernando Di Leo’s Mister Scarface (1976), Fabio Testi’s La Via Della Droga (1977) and Tomas Milian’s La Banda Del Trucido (1977).

As well as the real-life domestic influence, this sub-genre was also propelled by the success of American crime and action-films. Most notably, Francis Ford Coppola’s The Godfather (1971), which changed cinema forever and ignited a fervour for Mafia films.

On the outskirts of Poliziotteschi, leaning away from action and more towards the political, was Elio Petri’s sizzling and stylish satirical-thriller Investigation of a Citizen Above Suspicion (1970). The film, which showed last week as part of the BFI’s States of Danger and Deceit, strikes out at Italy’s corrupt police force and ridicules the absence of justice for the ordinary citizen.

Gian Maria Volonte plays a Murder Squad inspector who kills his mistress in the middle of a sexual encounter. He calmly manipulates the crime scene, intentionally leaving clues in his wake, before anonymously calling in the murder. The inept police officer on the other end of the call is a signifier for the lowly standard of police work to come in the remainder of the film.

The inspector, now promoted to work in the political section of the force, continues to push the boundaries of suspicion as numerous unwitting citizens are wrongly linked to the crime. At one point, the inspector’s fingerprints are found all over the crime scene, even in inexplicable places such as the shower room wall. Yet his position above suspicion means excuses have already been made for him.

The film’s opening images reference society’s pillars of justice and science. Both are absent or, at least, malfunctioning as the inspector skirts the line between misleading the investigation and blatantly giving himself away. He is, in his own words, driven by an indecisive illness caused by his ‘prolonged and permanent use of power’.

Flashbacks to his erotic encounters with victim Augusta (Florinda Bolkan) further reveal his frail ego and insecurities as this Polizia charade reaches a bitingly satirical conclusion.

Volonte’s central performance is a blend of formidable flair and sweaty nervousness. The former is best seen in his speech to fellow officers, in which he spells out the authoritarian nature of the police force at the time. He barks: ‘It is our duty to repress them [the people]. Repression is our remedy. Repression is civility.’

It is truly magnificent display from Volonte and alone worth finding a copy of the film for. As is the legendary Ennio Morricone’s score. It parallels the film brilliantly, with its driving thriller tones which are occasionally punctuated by the ‘boing oing oing’ of a jesting Jewish harp.

Investigation of a Citizen Above Suspicion should be on any cinema-lover’s must-watch list. It is even more timely with the current Paradise Papers’ revelations.

This is a film that cuttingly looks at a system of powerful people who think they are above human judgment – and more tellingly above the law.